In so far as a prosthesis is installed for a long period of time, it is important to ensure the rigidity and mechanical stability of a prosthesis component. If the screw is not tightened sufficiently during the positioning of the prosthesis, the risk of disassembly of the prosthetic component is aggravated.
EP-A-1 769 050 mentions the principle of locking a screw for controlling the displacement of a wedge-like ring which dilates a widened portion of an anchor stem of a prosthesis. This arrangement is specific to locking by means of a wedge-like ring. The means allowing such locking to be obtained are not described.